A. El Khatib et al.: Radioprotection 2026, 61( 2), 113 – 120 117
demonstrated that DLP values increase linearly with the number of scan phases and the scan length. Regarding the carotid CTA protocol, the increase in DRLs at Hospital B in terms of CTDI vol and DLP can be attributed to the specific acquisition parameters used. Hospital B employs a140 kV setting, a pitch of 0.984, and multiphasic protocols with three phases in 91 % of exams. These factors explain the observed rise in CTDI vol and DLP compared to Hospitals A, C, and D. Specifically, Hospital A uses a 120 kV setting, a pitch of 1.375, with three phases in 80 % of exams. Hospital C uses a 120 kV setting, a pitch of 1.375, with two phases in 45 % of exams. Hospital D uses a 110 kV setting, a pitch of 1.2, with one phase in 100 % of exams. Tube voltage( kV) significantly influences CT scans by impacting radiation dose and image quality. Lowering the tube voltage decreases radiation doses, with dose being proportional to the square of the tube current. Nijhof et al.( 2016) demonstrated that reducing tube voltage to 80 kVp reduces CTDI vol by 38 % in abdominal CTA. Fanous et al.( 2012) observed similar reductions with 100 kVp in pulmonary CTA for patients under 100 kg, achieving a 37 % reduction in CTDI vol compared to 120 kVp. During data collection, it was revealed that Hospital D used the lowest contrast agent volume among the hospitals, this possibly explaining its lower CTDI vol values. Ippolito et al.( 2015) confirmed that lower kV settings coupled with reduced contrast media volumes lower patient doses and CTDI vol. Using 100 kVp with 30 ml of contrast medium significantly reduces radiation doses while maintaining diagnostic quality.
For the pulmonary artery CTA protocol, the observed variations are attributed to the combination of adjusted parameters. Hospital C utilized the highest kV, with a voltage of 120 kV, compared to 110 kV in the other hospitals, which may account for the elevated CTDI vol observed at Hospital C. Conversely, Hospital B exhibited the highest DLP values, likely due to the use of two-phase protocols in 90 % of the exams for the pulmonary artery.
With regards to the abdominal aorta CTA protocol, the DRL values in terms of CTDI vol and DLP did not show significant differences between the three hospitals. Hospital B recorded the highest values, likely due to the use of two phases in 100 % of the examinations, whereas Hospitals A and C used two phases in 85 % and 50 % of the examinations, respectively.
With respect to the total aorta protocol, Hospital C presented the highest DRL values compared to Hospital A, with significant differences in terms of CTDI vol and DLP. This variation can be explained by the acquisition parameters: Hospital C used a voltage of 120 kV and three phases in 100 % of the examinations, whereas Hospital A used 110 kVand three phases in 60 % of the examinations.
As for the lower limb CTA protocol, Hospital B exhibited the highest LDRL values. This is attributed to the combination of acquisition parameters used, being the only hospital to use a voltage of 120 kV, while the other hospitals used 100 kV. Additionally, the number of phases was 2 in 88 % of the examinations at Hospital B, compared to 50 % at Hospital C and 1 phase in 100 % of the examinations at Hospital D. The pitch was 0.969 at Hospital B, compared to 1.375 at Hospital C and 1.5 at Hospital D. Notably, The integration of a high-pitch protocol with iterative reconstruction techniques enables substantial dose reduction( Gariani et al. 2018).
The recorded LDRLs were compared to existing studies in terms of CTDI vol and DLP. Our results demonstrate variability: some DRLs are comparable to those in previous studies, while others are either lower or higher.
As far as the brain CTA protocol is concerned, Hospital A shows CTDI vol values lower than those reported by Matsunaga et al.( 2019), Treier et al.( 2010), and Kim et al.( 2015), with differences of 65.5 %, 60 %, and 39 %, respectively. Conversely, the values are similar to those of Cho( 2013) and 47.5 % higher than those of Zensen et al.,( 2021). In comparison with Hospital B, the values are 30 % and 21 % lower than those of Matsunaga et al.( 2019) and Treier et al.( 2010), respectively, but 16 %, 26.7 %, and 73 % higher than those of Kim et al.( 2015), Cho( 2013), and Zensen et al.( 2021), respectively. In terms of DLP, the results from Hospitals A and B are lower than those of Kim et al.( 2015) and Cho( 2013), with respective differences of 26 – 24 % and 23 – 22 %. However, they are higher than those of Matsunaga et al.( 2019), Treier et al.( 2010), and Zensen et al.( 2021), with respective differences of 10-27-65 % and 13-29-66 %.
In relation to the carotid CTA protocol, the results from Hospitals C and D are lower than those of Treier et al.( 2010) and Aberle et al.( 2020) in terms of CTDI vol, with respective differences of 54.8 % and 17.54 %, and 70 % and 45.6 %, respectively. In contrast, Hospitals A and B show values 21 % and 43 % higher than those of Aberle et al.( 2020), but 30 % and 2.75 % lower than those of Treier et al.( 2010). In terms of DLP, the results from Hospitals A, B, C, and D are higher than those of Treier et al.( 2010), with differences ranging from 16 % to 62 %, and higher than those of Aberle et al.( 2020), with differences ranging from 39.5 % to 72 %.
For the pulmonary artery CTA protocol, all DRLs in terms of CTDI vol are lower than those reported in the published studies, with differences ranging from 21.8 % to 80 %. In terms of DLP, our results were comparable to those in previous studies, except for Hospital B, which showed a significantly higher value, with differences ranging from 19.2 % to 54.1 %.
As for the abdominal aorta CTA protocol, all DRLs in terms of CTDI vol are lower than those reported by Salama et al.,( 2017), Treier et al.( 2010), and Shrimpton et al.( 2018), with differences ranging from 19 % to 74 %. In terms of DLP, Hospital C shows a value 22.7 % lower than that of Salama et al.( 2017), but almost equivalent to that of Shrimpton et al.,( 2018). Hospitals A and B show significant differences compared to Treier et al.( 2010), with differences of 55.2 % and 51.4 %, respectively, and compared to Shrimpton et al.( 2018), with differences of 28.3 % and 22.1 %, respectively. The value recorded by Salama et al.( 2017) is similar to that of Hospital B, but differs from that of Hospital A by 9 %.
Regarding lower limb CTA, the LDRLs from our study in terms of CTDI vol and DLP are lower than the values reported in previous studies. For CTDI vol, our results show differences ranging from 56.2 % to 82.2 % compared to Salama et al.( 2017) and from 5 % to 61.5 % compared to Sulieman et al.( 2024). In terms of DLP, significant differences were observed when comparing the results of Sulieman et al.( 2024) with those from hospitals A, B, C, and D, with percentage differences of 83 %, 64.5 %, 75.8 %, and 79 %, respectively. In contrast, the comparison with the values from Salama et al.( 2017) shows differences of 54.4 %, 4.27 %, 34.6 %, and 45 %, respectively.